[lld] 10641a4 - Revert "[lld-macho] Support EH frames under arm64"
Douglas Yung via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 9 05:27:03 PDT 2022
Author: Douglas Yung
Date: 2022-06-09T05:24:28-07:00
New Revision: 10641a42e2286679e0d36ca827e1a40d95ae8ef1
URL: https://github.com/llvm/llvm-project/commit/10641a42e2286679e0d36ca827e1a40d95ae8ef1
DIFF: https://github.com/llvm/llvm-project/commit/10641a42e2286679e0d36ca827e1a40d95ae8ef1.diff
LOG: Revert "[lld-macho] Support EH frames under arm64"
This reverts commit 977d62c33e3343a394777c1754682761eebb66cd.
This change was causing crashes in 2 tests on the buildbots:
- https://lab.llvm.org/buildbot/#/builders/58/builds/23914
- https://lab.llvm.org/buildbot/#/builders/36/builds/21771
Added:
Modified:
lld/MachO/InputFiles.cpp
lld/test/MachO/eh-frame.s
Removed:
lld/test/MachO/Inputs/eh-frame-arm64-r.o
################################################################################
diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index 89405d21878a..16d019fb477b 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -1172,37 +1172,16 @@ static CIE parseCIE(const InputSection *isec, const EhReader &reader,
//
// Concretely, we expect our relocations to write the value of `PC -
// target_addr` to `PC`. `PC` itself is denoted by a minuend relocation that
-// points to a symbol plus an addend.
-//
-// It is important that the minuend relocation point to a symbol within the
-// same section as the fixup value, since sections may get moved around.
-//
-// For example, for arm64, llvm-mc emits relocations for the target function
-// address like so:
-//
-// ltmp:
-// <CIE start>
-// ...
-// <CIE end>
-// ... multiple FDEs ...
-// <FDE start>
-// <target function address - (ltmp + pcrel offset)>
-// ...
-//
-// If any of the FDEs in `multiple FDEs` get dead-stripped, then `FDE start`
-// will move to an earlier address, and `ltmp + pcrel offset` will no longer
-// reflect an accurate pcrel value. To avoid this problem, we "canonicalize"
-// our relocation by adding an `EH_Frame` symbol at `FDE start`, and updating
-// the reloc to be `target function address - (EH_Frame + new pcrel offset)`.
+// points to a symbol or section plus an addend.
//
// If `Invert` is set, then we instead expect `target_addr - PC` to be written
// to `PC`.
template <bool Invert = false>
Defined *
-targetSymFromCanonicalSubtractor(const InputSection *isec,
- std::vector<macho::Reloc>::iterator relocIt) {
- macho::Reloc &subtrahend = *relocIt;
- macho::Reloc &minuend = *std::next(relocIt);
+getTargetSymbolFromSubtraction(const InputSection *isec,
+ std::vector<macho::Reloc>::iterator relocIt) {
+ const macho::Reloc &subtrahend = *relocIt;
+ const macho::Reloc &minuend = *std::next(relocIt);
assert(target->hasAttr(subtrahend.type, RelocAttrBits::SUBTRAHEND));
assert(target->hasAttr(minuend.type, RelocAttrBits::UNSIGNED));
// Note: pcSym may *not* be exactly at the PC; there's usually a non-zero
@@ -1217,21 +1196,9 @@ targetSymFromCanonicalSubtractor(const InputSection *isec,
}
if (Invert)
std::swap(pcSym, target);
- if (pcSym->isec == isec) {
- if (pcSym->value - (Invert ? -1 : 1) * minuend.addend != subtrahend.offset)
- fatal("invalid FDE relocation in __eh_frame");
- } else {
- // Ensure the pcReloc points to a symbol within the current EH frame.
- // HACK: we should really verify that the original relocation's semantics
- // are preserved. In particular, we should have
- // `oldSym->value + oldOffset == newSym + newOffset`. However, we don't
- // have an easy way to access the offsets from this point in the code; some
- // refactoring is needed for that.
- macho::Reloc &pcReloc = Invert ? minuend : subtrahend;
- pcReloc.referent = isec->symbols[0];
- assert(isec->symbols[0]->value == 0);
- minuend.addend = pcReloc.offset * (Invert ? 1LL : -1LL);
- }
+ if (pcSym->isec != isec ||
+ pcSym->value - (Invert ? -1 : 1) * minuend.addend != subtrahend.offset)
+ fatal("invalid FDE relocation in __eh_frame");
return target;
}
@@ -1288,7 +1255,7 @@ void ObjFile::registerEhFrames(Section &ehFrameSection) {
if (cieOffRelocIt != isec->relocs.end()) {
// We already have an explicit relocation for the CIE offset.
cieIsec =
- targetSymFromCanonicalSubtractor</*Invert=*/true>(isec, cieOffRelocIt)
+ getTargetSymbolFromSubtraction</*Invert=*/true>(isec, cieOffRelocIt)
->isec;
dataOff += sizeof(uint32_t);
} else {
@@ -1343,7 +1310,7 @@ void ObjFile::registerEhFrames(Section &ehFrameSection) {
Defined *funcSym;
if (funcAddrRelocIt != isec->relocs.end()) {
- funcSym = targetSymFromCanonicalSubtractor(isec, funcAddrRelocIt);
+ funcSym = getTargetSymbolFromSubtraction(isec, funcAddrRelocIt);
} else {
funcSym = findSymbolAtAddress(sections, funcAddr);
ehRelocator.makePcRel(funcAddrOff, funcSym, target->p2WordSize);
@@ -1358,7 +1325,7 @@ void ObjFile::registerEhFrames(Section &ehFrameSection) {
InputSection *lsdaIsec = nullptr;
if (lsdaAddrRelocIt != isec->relocs.end()) {
- lsdaIsec = targetSymFromCanonicalSubtractor(isec, lsdaAddrRelocIt)->isec;
+ lsdaIsec = getTargetSymbolFromSubtraction(isec, lsdaAddrRelocIt)->isec;
} else if (lsdaAddrOpt) {
uint64_t lsdaAddr = *lsdaAddrOpt;
Section *sec = findContainingSection(sections, &lsdaAddr);
diff --git a/lld/test/MachO/Inputs/eh-frame-arm64-r.o b/lld/test/MachO/Inputs/eh-frame-arm64-r.o
deleted file mode 100644
index 15e73cacf71d..000000000000
Binary files a/lld/test/MachO/Inputs/eh-frame-arm64-r.o and /dev/null
diff er
diff --git a/lld/test/MachO/eh-frame.s b/lld/test/MachO/eh-frame.s
index 7437fdddbc0a..24fd7bfc93f9 100644
--- a/lld/test/MachO/eh-frame.s
+++ b/lld/test/MachO/eh-frame.s
@@ -20,18 +20,6 @@
# RUN: llvm-nm -m %t/eh-frame-x86_64-r | FileCheck %s --check-prefix NO-EH-SYMS
# RUN: llvm-readobj --section-headers %t/eh-frame-x86_64-r | FileCheck %s --check-prefix=ALIGN -D#ALIGN=3
-# RUN: llvm-mc -filetype=obj -triple=arm64-apple-macos11.0 %s -o %t/eh-frame-arm64.o
-# RUN: %lld -arch arm64 -lSystem -lc++ %t/eh-frame-arm64.o -o %t/eh-frame-arm64
-# RUN: llvm-objdump --macho --syms --indirect-symbols --unwind-info \
-# RUN: --dwarf=frames %t/eh-frame-arm64 | FileCheck %s -D#BASE=0x100000000 -D#DWARF_ENC=3
-# RUN: llvm-nm -m %t/eh-frame-arm64 | FileCheck %s --check-prefix NO-EH-SYMS
-
-# COM: ld -r %t/eh-frame-arm64.o -o %S/Inputs/eh-frame-arm64-r.o
-# RUN: %lld -arch arm64 -lSystem -lc++ %S/Inputs/eh-frame-arm64-r.o -o %t/eh-frame-arm64-r
-# RUN: llvm-objdump --macho --syms --indirect-symbols --unwind-info \
-# RUN: --dwarf=frames %t/eh-frame-arm64-r | FileCheck %s -D#BASE=0x100000000 -D#DWARF_ENC=3
-# RUN: llvm-nm -m %t/eh-frame-arm64-r | FileCheck %s --check-prefix NO-EH-SYMS
-
# ALIGN: Name: __eh_frame
# ALIGN-NEXT: Segment: __TEXT
# ALIGN-NEXT: Address:
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